AUV Control Mode Switching for Surface and Sub-Surface Navigation
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Solution Overview
Problem
Autonomous underwater vehicles (AUVs) face challenges in maintaining effective communication due to insufficient signal-to-noise ratios of acoustic waves, particularly when operating at sub-surface depths, which affects navigation and control.
Innovation Solution
A control system for AUVs that switches between surface and sub-surface modes, using radio signals in surface mode and deactivating the emergency stop function, and relying on acoustic signals and SONAR in sub-surface mode, with a switch triggered by pressure or manual command to adapt navigation based on environmental sensors or predefined paths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If acoustic waves are used for communication at sub-surface depth, then communication capability is maintained, but signal-to-noise ratio becomes insufficient due to propellor noise
Solution Approach 1:
The communication system is segmented into two independent modes: surface mode using radio waves and sub-surface mode using acoustic waves. The switch automatically selects the appropriate communication method based on the AUV's depth, ensuring reliable communication in each environment without the signal-to-noise ratio problems that occur when acoustic waves are used at the surface.
Solution Approach 2:
The system changes the communication parameter (communication medium) based on operating conditions. When the AUV transitions from surface to sub-surface operation, the system switches from radio wave communication to acoustic wave communication, optimizing communication performance for each depth regime and avoiding the propellor noise interference that affects acoustic signals at the surface.
2Loss of information
If radio signals are transmitted at surface, then communication quality is high, but communication fails at sub-surface depth
Solution Approach 1:
The control system is designed with multi-functionality to operate in two distinct communication modes. The system can function using radio waves when at the surface and switch to acoustic waves when submerged, making it universally adaptable to different operational environments and eliminating the limitation of single-mode communication systems.
Solution Approach 2:
The communication system is dynamic rather than static. A depth sensor continuously monitors the AUV's position, and when the AUV transitions between surface and sub-surface environments, the system automatically switches communication protocols. This dynamic adaptation ensures continuous high-quality communication regardless of the AUV's depth.
3Reliability
If emergency stop function is activated in surface mode, then safety is improved, but false stops occur when acoustic signals are unavailable
Solution Approach 1:
The emergency stop function has different activation characteristics in different operational modes. In surface mode, the system requires confirmation of signal loss before activating emergency stop, preventing false triggers from temporary radio signal interruptions. In sub-surface mode, the system is configured to not activate emergency stop due to acoustic signal unavailability, since acoustic communication is inherently less reliable underwater. This localized differentiation of safety response improves both safety and continuous operation capability.
4Device complexity
If switch between control modes is manual, then system complexity is reduced, but response time to environmental changes increases
Solution Approach 1:
The system incorporates a depth sensor that provides continuous feedback about the AUV's position. When the depth sensor detects that the AUV has transitioned between surface and sub-surface environments, it automatically triggers the appropriate control mode. This feedback mechanism eliminates the need for manual switching while keeping the system relatively simple, achieving both automatic rapid response and manageable complexity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables reliable navigation and control of AUVs both at the surface and sub-surface by leveraging radio signals and acoustic/SONAR, ensuring continuous operation and collision avoidance.
Implementation Method 1
The waypoints can be sent to the AUV using radio waves when at or near the surface
Implementation Method 2
using acoustic waves when at the sub-surface depth
Implementation Method 3
the sensor is a SONAR transceiver configured to transmit SONAR pulses and receive return SONAR signals
Data Source
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AI summary
The present invention relates to a control system for an autonomous underwater vehicle, AUV. The control system comprises: a controller configured to operate: in a surface control mode to transmit periodic signals from a transmitter of the AUV, control the AUV to move based on the return signals when return signals are received via a receiver of the AUV, and activate an emergency stop function to stop the AUV when the return signals are absent, and in a sub-surface control mode to not transmit the periodic signals, de-activate the emergency stop function, and control the AUV to move based on the return signals received when operating in the surface control mode; and a switch to switch between the surface control mode and the sub-surface control mode.